This jump is a good technique to avoid being sealed in. Black cannot cut off the stone:
White must capture the cutting stone with and
, leaving her a and b to connect.
Bill: So Black may play , inviting
. (If White replies at
instead, she does not get the ponnuki of the previous diagram: see next diagram.)
Velobici: White can prevent the cut with . Black can not play at
in place of
, for White will play at
.
then
... maybe White doesn't want to commit suicide.